77158991521 has 2 divisors, whose sum is σ = 77158991522. Its totient is φ = 77158991520.

The previous prime is 77158991477. The next prime is 77158991563. The reversal of 77158991521 is 12519985177.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76818219921 + 340771600 = 277161^2 + 18460^2 .

It is a cyclic number.

It is not a de Polignac number, because 77158991521 - 2²⁹ = 76622120609 is a prime.

It is not a weakly prime, because it can be changed into another prime (77158911521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38579495760 + 38579495761.

It is an arithmetic number, because the mean of its divisors is an integer number (38579495761).

Almost surely, 2^77158991521 is an apocalyptic number.

It is an amenable number.

77158991521 is a deficient number, since it is larger than the sum of its proper divisors (1).

77158991521 is an equidigital number, since it uses as much as digits as its factorization.

77158991521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1587600, while the sum is 55.

The spelling of 77158991521 in words is "seventy-seven billion, one hundred fifty-eight million, nine hundred ninety-one thousand, five hundred twenty-one".